Note:

Abstract: Dynamic speed limits can be used to eliminate shockwaves on freeways. Shockwaves are typically short traffic jams that emerge at bottlenecks and travel in the upstream direction on the freeway. These shockwaves lead to increased travel times and possibly to unsafe situations. A speed limit control approach to resolving shockwaves was developed based on a distributed controller design technique. The controller is distributed in the sense that each speed limit sign has its own controller. The controller parameters are optimized by numerical optimization, assuming that the controller structure and parameters are the same for each controller. The resulting performances are compared for several designs, differing in the controller order and the extent that the upstream and downstream traffic states are used as inputs for the controller. Other controllers known from the literature are based on switching schemes using local information only or are centralized model-based controllers with high computational loads. The proposed method gives a systematic way to design distributed controllers using the appropriate amount of upstream and downstream traffic information. The resulting controllers are attractive from the implementation point of view because they are very efficient. They do not require extensive online computations and use only information from the neighborhood. For the design scenario used, the controller successfully resolved the shockwave and reduced the total time spent by approximately 20{\%} compared with the uncontrolled case, which is comparable to the performance of the best controllers known from the literature.

Note:

Abstract: Dynamic speed limits can be used to eliminate shockwaves on freeways. Shockwaves are typically short traffic jams that emerge at bottlenecks and travel in the upstream direction on the freeway. These shockwaves lead to increased travel times and possibly to unsafe situations. A speed limit control approach to resolving shockwaves was developed based on a distributed controller design technique. The controller is distributed in the sense that each speed limit sign has its own controller. The controller parameters are optimized by numerical optimization, assuming that the controller structure and parameters are the same for each controller. The resulting performances are compared for several designs, differing in the controller order and the extent that the upstream and downstream traffic states are used as inputs for the controller. Other controllers known from the literature are based on switching schemes using local information only or are centralized model-based controllers with high computational loads. The proposed method gives a systematic way to design distributed controllers using the appropriate amount of upstream and downstream traffic information. The resulting controllers are attractive from the implementation point of view because they are very efficient. They do not require extensive online computations and use only information from the neighborhood. For the design scenario used, the controller successfully resolved the shockwave and reduced the total time spent by approximately 20{\%} compared with the uncontrolled case, which is comparable to the performance of the best controllers known from the literature.